We were trying to make an addition function that, unlike the library one,
could add numbers of different types from the typeclass 'Num.' We originally
ran into a problem when trying to add (5 :: Integer) + 4.8, and were trying
to define a new function that would be able to get that:
(+') :: (Num a, Num b) => a -> b -> Float
x +' b = d + e
where d :: Float
d = x
e :: Float
e = b
This gave us the error:
Couldn't match expected type `Float' against inferred type `b'
`b' is a rigid type variable bound by
the type signature for `pl' at test.hs:9:18
In the expression: b
In the definition of `e': e = b
In the definition of `pl':
pl x b
= d + e
where
d :: Float
d = x
e :: Float
e = b
Failed, modules loaded: none.
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